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using System;
using System.Collections;
using System.IO;
using System.Text;
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Nist;
using Org.BouncyCastle.Asn1.Pkcs;
using Org.BouncyCastle.Asn1.TeleTrust;
using Org.BouncyCastle.Asn1.Utilities;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Encodings;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.Crypto.Signers;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Signers
{
public class RsaDigestSigner
: ISigner
{
private readonly IAsymmetricBlockCipher rsaEngine = new Pkcs1Encoding(new RsaBlindedEngine());
private readonly AlgorithmIdentifier algId;
private readonly IDigest digest;
private bool forSigning;
private static readonly IDictionary oidMap = Platform.CreateHashtable();
/// <summary>
/// Load oid table.
/// </summary>
static RsaDigestSigner()
{
oidMap["RIPEMD128"] = TeleTrusTObjectIdentifiers.RipeMD128;
oidMap["RIPEMD160"] = TeleTrusTObjectIdentifiers.RipeMD160;
oidMap["RIPEMD256"] = TeleTrusTObjectIdentifiers.RipeMD256;
oidMap["SHA-1"] = X509ObjectIdentifiers.IdSha1;
oidMap["SHA-224"] = NistObjectIdentifiers.IdSha224;
oidMap["SHA-256"] = NistObjectIdentifiers.IdSha256;
oidMap["SHA-384"] = NistObjectIdentifiers.IdSha384;
oidMap["SHA-512"] = NistObjectIdentifiers.IdSha512;
oidMap["MD2"] = PkcsObjectIdentifiers.MD2;
oidMap["MD4"] = PkcsObjectIdentifiers.MD4;
oidMap["MD5"] = PkcsObjectIdentifiers.MD5;
}
public RsaDigestSigner(
IDigest digest)
{
this.digest = digest;
string algName = digest.AlgorithmName;
if (algName.Equals("NULL"))
{
this.algId = null;
}
else
{
this.algId = new AlgorithmIdentifier(
(DerObjectIdentifier)oidMap[digest.AlgorithmName], DerNull.Instance);
}
}
public string AlgorithmName
{
get { return digest.AlgorithmName + "withRSA"; }
}
/**
* Initialise the signer for signing or verification.
*
* @param forSigning true if for signing, false otherwise
* @param param necessary parameters.
*/
public void Init(
bool forSigning,
ICipherParameters parameters)
{
this.forSigning = forSigning;
AsymmetricKeyParameter k;
if (parameters is ParametersWithRandom)
{
k = (AsymmetricKeyParameter)((ParametersWithRandom)parameters).Parameters;
}
else
{
k = (AsymmetricKeyParameter)parameters;
}
if (forSigning && !k.IsPrivate)
throw new InvalidKeyException("Signing requires private key.");
if (!forSigning && k.IsPrivate)
throw new InvalidKeyException("Verification requires public key.");
Reset();
rsaEngine.Init(forSigning, parameters);
}
/**
* update the internal digest with the byte b
*/
public void Update(
byte input)
{
digest.Update(input);
}
/**
* update the internal digest with the byte array in
*/
public void BlockUpdate(
byte[] input,
int inOff,
int length)
{
digest.BlockUpdate(input, inOff, length);
}
/**
* Generate a signature for the message we've been loaded with using
* the key we were initialised with.
*/
public byte[] GenerateSignature()
{
if (!forSigning)
throw new InvalidOperationException("RsaDigestSigner not initialised for signature generation.");
byte[] hash = new byte[digest.GetDigestSize()];
digest.DoFinal(hash, 0);
byte[] data = DerEncode(hash);
return rsaEngine.ProcessBlock(data, 0, data.Length);
}
/**
* return true if the internal state represents the signature described
* in the passed in array.
*/
public bool VerifySignature(
byte[] signature)
{
if (forSigning)
throw new InvalidOperationException("RsaDigestSigner not initialised for verification");
byte[] hash = new byte[digest.GetDigestSize()];
digest.DoFinal(hash, 0);
byte[] sig;
byte[] expected;
try
{
sig = rsaEngine.ProcessBlock(signature, 0, signature.Length);
expected = DerEncode(hash);
}
catch (Exception)
{
return false;
}
if (sig.Length == expected.Length)
{
for (int i = 0; i < sig.Length; i++)
{
if (sig[i] != expected[i])
{
return false;
}
}
}
else if (sig.Length == expected.Length - 2) // NULL left out
{
int sigOffset = sig.Length - hash.Length - 2;
int expectedOffset = expected.Length - hash.Length - 2;
expected[1] -= 2; // adjust lengths
expected[3] -= 2;
for (int i = 0; i < hash.Length; i++)
{
if (sig[sigOffset + i] != expected[expectedOffset + i]) // check hash
{
return false;
}
}
for (int i = 0; i < sigOffset; i++)
{
if (sig[i] != expected[i]) // check header less NULL
{
return false;
}
}
}
else
{
return false;
}
return true;
}
public void Reset()
{
digest.Reset();
}
private byte[] DerEncode(byte[] hash)
{
if (algId == null)
{
// For raw RSA, the DigestInfo must be prepared externally
return hash;
}
DigestInfo dInfo = new DigestInfo(algId, hash);
return dInfo.GetDerEncoded();
}
}
}
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